O2 Sensor Question

I have two different O2 sensors in my car. One is a black sleeve over the wires and has three wires, the other is a white sleeve and has four wires. I was under the impression that EECIV wiring was set up for a 3 wire sensor. My buddy put in the 4 wire when we got ready for the first fire up after the rebuild. Since then I've had a miss and my passenger bank( the one with the odd sensor) reeks of fuel. Could the four wire sensor be the culprit?

To the best of my knowledge you need the 3 wire. I replaced on of mine about a year ago. The 4 wire O2 are grounded through the harness, while the 3 wire O2 sensors ground through the body.

Wiring is as follows
gray wire is the ground
black is signal
white wires are heater

If you tried to use the 4 wire on a three wire car, you don't have a ground. The connector will actually plug in, but the mating connector on the car harness will not provide a ground and you can fry your EEC.

yes, all my codes were for my smog pump and charcoal canister which have been removed. Had one for the TPS but that has been fixed. I plan on replacing both sensors, will pull codes and report back after that.

SN Certified TechnicianFounding Member

I have two different O2 sensors in my car. One is a black sleeve over the wires and has three wires, the other is a white sleeve and has four wires. I was under the impression that EECIV wiring was set up for a 3 wire sensor. My buddy put in the 4 wire when we got ready for the first fire up after the rebuild. Since then I've had a miss and my passenger bank( the one with the odd sensor) reeks of fuel. Could the four wire sensor be the culprit?

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The 4 wire sensors are for the 4 cylinder cars. The extra wire is a ground, and I don't know if it is the sensor ground or the heater ground. You need 2 good O2 sensors with the 3 wire setup that the 5.0 Fox Mustangs use.